长期下尿路梗阻的继发声像图改变，应除外（）
A.膀胱小梁化
B.膀胱憩室
C.膀胱结石
D.双肾积水
E.前列腺增生
参考答案：E
— What did you think of Act I of the play last night?
— I’m sorry. The play ________ when I got there.
A．had been started
B．had been on for half an hour
C．was to start
D．had begun for half an hour
简述瓦管的优缺点？
